提交 433de739 编写于 作者: H H. Peter Anvin

x86, realmode: 16-bit real-mode code support for relocs tool

A new option is added to the relocs tool called '--realmode'.
This option causes the generation of 16-bit segment relocations
and 32-bit linear relocations for the real-mode code. When
the real-mode code is moved to the low-memory during kernel
initialization, these relocation entries can be used to
relocate the code properly.

In the assembly code 16-bit segment relocations must be relative
to the 'real_mode_seg' absolute symbol. Linear relocations must be
relative to a symbol prefixed with 'pa_'.

16-bit segment relocation is used to load cs:ip in 16-bit code.
Linear relocations are used in the 32-bit code for relocatable
data references. They are declared in the linker script of the
real-mode code.

The relocs tool is moved to scripts/x86-relocs.c so it will
be compiled before building the arch/x86 tree.
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1336501366-28617-2-git-send-email-jarkko.sakkinen@intel.comSigned-off-by: NJarkko Sakkinen <jarkko.sakkinen@intel.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
上级 d48b97b4
...@@ -40,13 +40,12 @@ OBJCOPYFLAGS_vmlinux.bin := -R .comment -S ...@@ -40,13 +40,12 @@ OBJCOPYFLAGS_vmlinux.bin := -R .comment -S
$(obj)/vmlinux.bin: vmlinux FORCE $(obj)/vmlinux.bin: vmlinux FORCE
$(call if_changed,objcopy) $(call if_changed,objcopy)
targets += vmlinux.bin.all vmlinux.relocs
targets += vmlinux.bin.all vmlinux.relocs relocs CMD_RELOCS = scripts/x86-relocs
hostprogs-$(CONFIG_X86_NEED_RELOCS) += relocs quiet_cmd_relocs = RELOCS $@
cmd_relocs = $(CMD_RELOCS) $< > $@;$(CMD_RELOCS) --abs-relocs $<
quiet_cmd_relocs = RELOCS $@ $(obj)/vmlinux.relocs: vmlinux FORCE
cmd_relocs = $(obj)/relocs $< > $@;$(obj)/relocs --abs-relocs $<
$(obj)/vmlinux.relocs: vmlinux $(obj)/relocs FORCE
$(call if_changed,relocs) $(call if_changed,relocs)
vmlinux.bin.all-y := $(obj)/vmlinux.bin vmlinux.bin.all-y := $(obj)/vmlinux.bin
......
...@@ -9,3 +9,4 @@ unifdef ...@@ -9,3 +9,4 @@ unifdef
ihex2fw ihex2fw
recordmcount recordmcount
docproc docproc
x86-relocs
...@@ -8,11 +8,14 @@ ...@@ -8,11 +8,14 @@
# conmakehash: Create arrays for initializing the kernel console tables # conmakehash: Create arrays for initializing the kernel console tables
# docproc: Used in Documentation/DocBook # docproc: Used in Documentation/DocBook
HOST_EXTRACFLAGS += -I$(srctree)/tools/include
hostprogs-$(CONFIG_KALLSYMS) += kallsyms hostprogs-$(CONFIG_KALLSYMS) += kallsyms
hostprogs-$(CONFIG_LOGO) += pnmtologo hostprogs-$(CONFIG_LOGO) += pnmtologo
hostprogs-$(CONFIG_VT) += conmakehash hostprogs-$(CONFIG_VT) += conmakehash
hostprogs-$(CONFIG_IKCONFIG) += bin2c hostprogs-$(CONFIG_IKCONFIG) += bin2c
hostprogs-$(BUILD_C_RECORDMCOUNT) += recordmcount hostprogs-$(BUILD_C_RECORDMCOUNT) += recordmcount
hostprogs-$(CONFIG_X86) += x86-relocs
always := $(hostprogs-y) $(hostprogs-m) always := $(hostprogs-y) $(hostprogs-m)
......
...@@ -18,6 +18,8 @@ static void die(char *fmt, ...); ...@@ -18,6 +18,8 @@ static void die(char *fmt, ...);
static Elf32_Ehdr ehdr; static Elf32_Ehdr ehdr;
static unsigned long reloc_count, reloc_idx; static unsigned long reloc_count, reloc_idx;
static unsigned long *relocs; static unsigned long *relocs;
static unsigned long reloc16_count, reloc16_idx;
static unsigned long *relocs16;
struct section { struct section {
Elf32_Shdr shdr; Elf32_Shdr shdr;
...@@ -28,52 +30,82 @@ struct section { ...@@ -28,52 +30,82 @@ struct section {
}; };
static struct section *secs; static struct section *secs;
enum symtype {
S_ABS,
S_REL,
S_SEG,
S_LIN,
S_NSYMTYPES
};
static const char * const sym_regex_kernel[S_NSYMTYPES] = {
/* /*
* Following symbols have been audited. There values are constant and do * Following symbols have been audited. There values are constant and do
* not change if bzImage is loaded at a different physical address than * not change if bzImage is loaded at a different physical address than
* the address for which it has been compiled. Don't warn user about * the address for which it has been compiled. Don't warn user about
* absolute relocations present w.r.t these symbols. * absolute relocations present w.r.t these symbols.
*/ */
static const char abs_sym_regex[] = [S_ABS] =
"^(xen_irq_disable_direct_reloc$|" "^(xen_irq_disable_direct_reloc$|"
"xen_save_fl_direct_reloc$|" "xen_save_fl_direct_reloc$|"
"VDSO|" "VDSO|"
"__crc_)"; "__crc_)",
static regex_t abs_sym_regex_c;
static int is_abs_reloc(const char *sym_name)
{
return !regexec(&abs_sym_regex_c, sym_name, 0, NULL, 0);
}
/* /*
* These symbols are known to be relative, even if the linker marks them * These symbols are known to be relative, even if the linker marks them
* as absolute (typically defined outside any section in the linker script.) * as absolute (typically defined outside any section in the linker script.)
*/ */
static const char rel_sym_regex[] = [S_REL] =
"^_end$"; "^_end$",
static regex_t rel_sym_regex_c; };
static int is_rel_reloc(const char *sym_name)
static const char * const sym_regex_realmode[S_NSYMTYPES] = {
/*
* These are 16-bit segment symbols when compiling 16-bit code.
*/
[S_SEG] =
"^real_mode_seg$",
/*
* These are offsets belonging to segments, as opposed to linear addresses,
* when compiling 16-bit code.
*/
[S_LIN] =
"^pa_",
};
static const char * const *sym_regex;
static regex_t sym_regex_c[S_NSYMTYPES];
static int is_reloc(enum symtype type, const char *sym_name)
{ {
return !regexec(&rel_sym_regex_c, sym_name, 0, NULL, 0); return sym_regex[type] &&
!regexec(&sym_regex_c[type], sym_name, 0, NULL, 0);
} }
static void regex_init(void) static void regex_init(int use_real_mode)
{ {
char errbuf[128]; char errbuf[128];
int err; int err;
int i;
err = regcomp(&abs_sym_regex_c, abs_sym_regex,
REG_EXTENDED|REG_NOSUB);
if (err) {
regerror(err, &abs_sym_regex_c, errbuf, sizeof errbuf);
die("%s", errbuf);
}
err = regcomp(&rel_sym_regex_c, rel_sym_regex, if (use_real_mode)
REG_EXTENDED|REG_NOSUB); sym_regex = sym_regex_realmode;
if (err) { else
regerror(err, &rel_sym_regex_c, errbuf, sizeof errbuf); sym_regex = sym_regex_kernel;
die("%s", errbuf);
for (i = 0; i < S_NSYMTYPES; i++) {
if (!sym_regex[i])
continue;
err = regcomp(&sym_regex_c[i], sym_regex[i],
REG_EXTENDED|REG_NOSUB);
if (err) {
regerror(err, &sym_regex_c[i], errbuf, sizeof errbuf);
die("%s", errbuf);
}
} }
} }
...@@ -154,6 +186,10 @@ static const char *rel_type(unsigned type) ...@@ -154,6 +186,10 @@ static const char *rel_type(unsigned type)
REL_TYPE(R_386_RELATIVE), REL_TYPE(R_386_RELATIVE),
REL_TYPE(R_386_GOTOFF), REL_TYPE(R_386_GOTOFF),
REL_TYPE(R_386_GOTPC), REL_TYPE(R_386_GOTPC),
REL_TYPE(R_386_8),
REL_TYPE(R_386_PC8),
REL_TYPE(R_386_16),
REL_TYPE(R_386_PC16),
#undef REL_TYPE #undef REL_TYPE
}; };
const char *name = "unknown type rel type name"; const char *name = "unknown type rel type name";
...@@ -189,7 +225,7 @@ static const char *sym_name(const char *sym_strtab, Elf32_Sym *sym) ...@@ -189,7 +225,7 @@ static const char *sym_name(const char *sym_strtab, Elf32_Sym *sym)
name = sym_strtab + sym->st_name; name = sym_strtab + sym->st_name;
} }
else { else {
name = sec_name(secs[sym->st_shndx].shdr.sh_name); name = sec_name(sym->st_shndx);
} }
return name; return name;
} }
...@@ -472,7 +508,7 @@ static void print_absolute_relocs(void) ...@@ -472,7 +508,7 @@ static void print_absolute_relocs(void)
* Before warning check if this absolute symbol * Before warning check if this absolute symbol
* relocation is harmless. * relocation is harmless.
*/ */
if (is_abs_reloc(name) || is_rel_reloc(name)) if (is_reloc(S_ABS, name) || is_reloc(S_REL, name))
continue; continue;
if (!printed) { if (!printed) {
...@@ -496,7 +532,8 @@ static void print_absolute_relocs(void) ...@@ -496,7 +532,8 @@ static void print_absolute_relocs(void)
printf("\n"); printf("\n");
} }
static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym)) static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym),
int use_real_mode)
{ {
int i; int i;
/* Walk through the relocations */ /* Walk through the relocations */
...@@ -521,30 +558,62 @@ static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym)) ...@@ -521,30 +558,62 @@ static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym))
Elf32_Rel *rel; Elf32_Rel *rel;
Elf32_Sym *sym; Elf32_Sym *sym;
unsigned r_type; unsigned r_type;
const char *symname;
rel = &sec->reltab[j]; rel = &sec->reltab[j];
sym = &sh_symtab[ELF32_R_SYM(rel->r_info)]; sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
r_type = ELF32_R_TYPE(rel->r_info); r_type = ELF32_R_TYPE(rel->r_info);
/* Don't visit relocations to absolute symbols */
if (sym->st_shndx == SHN_ABS &&
!is_rel_reloc(sym_name(sym_strtab, sym))) {
continue;
}
switch (r_type) { switch (r_type) {
case R_386_NONE: case R_386_NONE:
case R_386_PC32: case R_386_PC32:
case R_386_PC16:
case R_386_PC8:
/* /*
* NONE can be ignored and and PC relative * NONE can be ignored and and PC relative
* relocations don't need to be adjusted. * relocations don't need to be adjusted.
*/ */
break; break;
case R_386_16:
symname = sym_name(sym_strtab, sym);
if (!use_real_mode)
goto bad;
if (sym->st_shndx == SHN_ABS) {
if (is_reloc(S_ABS, symname))
break;
else if (!is_reloc(S_SEG, symname))
goto bad;
} else {
if (is_reloc(S_LIN, symname))
goto bad;
else
break;
}
visit(rel, sym);
break;
case R_386_32: case R_386_32:
/* Visit relocations that need to be adjusted */ symname = sym_name(sym_strtab, sym);
if (sym->st_shndx == SHN_ABS) {
if (is_reloc(S_ABS, symname))
break;
else if (!is_reloc(S_REL, symname))
goto bad;
} else {
if (use_real_mode &&
!is_reloc(S_LIN, symname))
break;
}
visit(rel, sym); visit(rel, sym);
break; break;
default: default:
die("Unsupported relocation type: %s (%d)\n", die("Unsupported relocation type: %s (%d)\n",
rel_type(r_type), r_type); rel_type(r_type), r_type);
break; break;
bad:
symname = sym_name(sym_strtab, sym);
die("Invalid %s relocation: %s\n",
rel_type(r_type), symname);
} }
} }
} }
...@@ -552,13 +621,19 @@ static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym)) ...@@ -552,13 +621,19 @@ static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym))
static void count_reloc(Elf32_Rel *rel, Elf32_Sym *sym) static void count_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
{ {
reloc_count += 1; if (ELF32_R_TYPE(rel->r_info) == R_386_16)
reloc16_count++;
else
reloc_count++;
} }
static void collect_reloc(Elf32_Rel *rel, Elf32_Sym *sym) static void collect_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
{ {
/* Remember the address that needs to be adjusted. */ /* Remember the address that needs to be adjusted. */
relocs[reloc_idx++] = rel->r_offset; if (ELF32_R_TYPE(rel->r_info) == R_386_16)
relocs16[reloc16_idx++] = rel->r_offset;
else
relocs[reloc_idx++] = rel->r_offset;
} }
static int cmp_relocs(const void *va, const void *vb) static int cmp_relocs(const void *va, const void *vb)
...@@ -568,23 +643,41 @@ static int cmp_relocs(const void *va, const void *vb) ...@@ -568,23 +643,41 @@ static int cmp_relocs(const void *va, const void *vb)
return (*a == *b)? 0 : (*a > *b)? 1 : -1; return (*a == *b)? 0 : (*a > *b)? 1 : -1;
} }
static void emit_relocs(int as_text) static int write32(unsigned int v, FILE *f)
{
unsigned char buf[4];
put_unaligned_le32(v, buf);
return fwrite(buf, 1, 4, f) == 4 ? 0 : -1;
}
static void emit_relocs(int as_text, int use_real_mode)
{ {
int i; int i;
/* Count how many relocations I have and allocate space for them. */ /* Count how many relocations I have and allocate space for them. */
reloc_count = 0; reloc_count = 0;
walk_relocs(count_reloc); walk_relocs(count_reloc, use_real_mode);
relocs = malloc(reloc_count * sizeof(relocs[0])); relocs = malloc(reloc_count * sizeof(relocs[0]));
if (!relocs) { if (!relocs) {
die("malloc of %d entries for relocs failed\n", die("malloc of %d entries for relocs failed\n",
reloc_count); reloc_count);
} }
relocs16 = malloc(reloc16_count * sizeof(relocs[0]));
if (!relocs16) {
die("malloc of %d entries for relocs16 failed\n",
reloc16_count);
}
/* Collect up the relocations */ /* Collect up the relocations */
reloc_idx = 0; reloc_idx = 0;
walk_relocs(collect_reloc); walk_relocs(collect_reloc, use_real_mode);
if (reloc16_count && !use_real_mode)
die("Segment relocations found but --realmode not specified\n");
/* Order the relocations for more efficient processing */ /* Order the relocations for more efficient processing */
qsort(relocs, reloc_count, sizeof(relocs[0]), cmp_relocs); qsort(relocs, reloc_count, sizeof(relocs[0]), cmp_relocs);
qsort(relocs16, reloc16_count, sizeof(relocs16[0]), cmp_relocs);
/* Print the relocations */ /* Print the relocations */
if (as_text) { if (as_text) {
...@@ -593,58 +686,83 @@ static void emit_relocs(int as_text) ...@@ -593,58 +686,83 @@ static void emit_relocs(int as_text)
*/ */
printf(".section \".data.reloc\",\"a\"\n"); printf(".section \".data.reloc\",\"a\"\n");
printf(".balign 4\n"); printf(".balign 4\n");
for (i = 0; i < reloc_count; i++) { if (use_real_mode) {
printf("\t .long 0x%08lx\n", relocs[i]); printf("\t.long %lu\n", reloc16_count);
for (i = 0; i < reloc16_count; i++)
printf("\t.long 0x%08lx\n", relocs16[i]);
printf("\t.long %lu\n", reloc_count);
for (i = 0; i < reloc_count; i++) {
printf("\t.long 0x%08lx\n", relocs[i]);
}
} else {
/* Print a stop */
printf("\t.long 0x%08lx\n", (unsigned long)0);
for (i = 0; i < reloc_count; i++) {
printf("\t.long 0x%08lx\n", relocs[i]);
}
} }
printf("\n"); printf("\n");
} }
else { else {
unsigned char buf[4]; if (use_real_mode) {
/* Print a stop */ write32(reloc16_count, stdout);
fwrite("\0\0\0\0", 4, 1, stdout); for (i = 0; i < reloc16_count; i++)
/* Now print each relocation */ write32(relocs16[i], stdout);
for (i = 0; i < reloc_count; i++) { write32(reloc_count, stdout);
put_unaligned_le32(relocs[i], buf);
fwrite(buf, 4, 1, stdout); /* Now print each relocation */
for (i = 0; i < reloc_count; i++)
write32(relocs[i], stdout);
} else {
/* Print a stop */
write32(0, stdout);
/* Now print each relocation */
for (i = 0; i < reloc_count; i++) {
write32(relocs[i], stdout);
}
} }
} }
} }
static void usage(void) static void usage(void)
{ {
die("relocs [--abs-syms |--abs-relocs | --text] vmlinux\n"); die("relocs [--abs-syms|--abs-relocs|--text|--realmode] vmlinux\n");
} }
int main(int argc, char **argv) int main(int argc, char **argv)
{ {
int show_absolute_syms, show_absolute_relocs; int show_absolute_syms, show_absolute_relocs;
int as_text; int as_text, use_real_mode;
const char *fname; const char *fname;
FILE *fp; FILE *fp;
int i; int i;
regex_init();
show_absolute_syms = 0; show_absolute_syms = 0;
show_absolute_relocs = 0; show_absolute_relocs = 0;
as_text = 0; as_text = 0;
use_real_mode = 0;
fname = NULL; fname = NULL;
for (i = 1; i < argc; i++) { for (i = 1; i < argc; i++) {
char *arg = argv[i]; char *arg = argv[i];
if (*arg == '-') { if (*arg == '-') {
if (strcmp(argv[1], "--abs-syms") == 0) { if (strcmp(arg, "--abs-syms") == 0) {
show_absolute_syms = 1; show_absolute_syms = 1;
continue; continue;
} }
if (strcmp(arg, "--abs-relocs") == 0) {
if (strcmp(argv[1], "--abs-relocs") == 0) {
show_absolute_relocs = 1; show_absolute_relocs = 1;
continue; continue;
} }
else if (strcmp(argv[1], "--text") == 0) { if (strcmp(arg, "--text") == 0) {
as_text = 1; as_text = 1;
continue; continue;
} }
if (strcmp(arg, "--realmode") == 0) {
use_real_mode = 1;
continue;
}
} }
else if (!fname) { else if (!fname) {
fname = arg; fname = arg;
...@@ -655,6 +773,7 @@ int main(int argc, char **argv) ...@@ -655,6 +773,7 @@ int main(int argc, char **argv)
if (!fname) { if (!fname) {
usage(); usage();
} }
regex_init(use_real_mode);
fp = fopen(fname, "r"); fp = fopen(fname, "r");
if (!fp) { if (!fp) {
die("Cannot open %s: %s\n", die("Cannot open %s: %s\n",
...@@ -673,6 +792,6 @@ int main(int argc, char **argv) ...@@ -673,6 +792,6 @@ int main(int argc, char **argv)
print_absolute_relocs(); print_absolute_relocs();
return 0; return 0;
} }
emit_relocs(as_text); emit_relocs(as_text, use_real_mode);
return 0; return 0;
} }
Markdown is supported
0% .
You are about to add 0 people to the discussion. Proceed with caution.
先完成此消息的编辑!
想要评论请 注册